import Vue from 'vue';
Vue.directive('dialogDrag', {
  bind(el, binding, vnode, oldVnode) {
    const dialogHeaderEl = el.querySelector('.el-dialog__header');
    const dragDom = el.querySelector('.el-dialog');
    dialogHeaderEl.style.cssText += ';cursor:move;'
    dragDom.style.cssText += ';top:0px;'
    const sty = (function() {
        if ((window.document as any).currentStyle) {
            return (dom, attr) => dom.currentStyle[attr];
        } else{
            return (dom, attr) => getComputedStyle(dom, '')[attr];
        }
    })()    
     
    dialogHeaderEl.onmousedown = (e) => {
        const disX = e.clientX - dialogHeaderEl.offsetLeft;
        const disY = e.clientY - dialogHeaderEl.offsetTop;
        const screenWidth = document.body.clientWidth; // body当前宽度
        const screenHeight = document.documentElement.clientHeight; // 可见区域高度(应为body高度，可某些环境下无法获取) 
        const dragDomWidth = dragDom.offsetWidth; // 对话框宽度
        const dragDomheight = dragDom.offsetHeight; // 对话框高度
        const minDragDomLeft = dragDom.offsetLeft;
        const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;
        const minDragDomTop = dragDom.offsetTop;
        const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight;
        // 获取到的值带px 正则匹配替换
        let styL = sty(dragDom, 'left');
        let styT = sty(dragDom, 'top');
        // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
        if(styL.includes('%')) {
            styL = +document.body.clientWidth * (+styL.replace(/%/g,'') / 100);
            styT = +document.body.clientHeight * (+styT.replace(/%/g, '') / 100);
        }else {
            styL = +styL.replace(/\px/g, '');
            styT = +styT.replace(/\px/g, '');
      }
      document.onmousemove = function (e) {
            let left = e.clientX - disX;
            let top = e.clientY - disY;
            if (-(left) > minDragDomLeft) {
                left = -(minDragDomLeft);
            } else if (left > maxDragDomLeft) {
                left = maxDragDomLeft;
            }
            if (-(top) > minDragDomTop) {
                top = -(minDragDomTop);
            } else if (top > maxDragDomTop) {
                top = maxDragDomTop;
            }
            dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`;
      };
  
      document.onmouseup = function (e) {
          document.onmousemove = null;
          document.onmouseup = null;
      };
    } 
  }
})